The glucuronide of 4-aminobiphenyl has been isolated in apparently pure form. Single peaks were obtained on 5 different HPLC columns. Efforts to synthesize this metabolite have not been successful. We are currently attempting to prepare the tri-fluoroacetyl hydroxamic acid which should allow us to remove the acetyl group more readily after conjugation. The conjugate isolated from dog urine has been found to be highly mutagenic in TA-1538, especially at pH 5. This strain also gives a strongly positive mutagenic effect with 4-nitrosobiphenyl and N-hydroxy-4-aminobiphenyl. The reactions of the C-14 labelled metabolites with salmon sperm DNA have been studied in vitro. Although some degree of binding appears to occur, no specific reaction product could be detected after enzymatic hydrolysis. Next we will study binding with poly G and poly GC. We are also reacting the C-14 labelled N-hydroxy and nitroso compounds with intact S. typhimurium TA-1538. The nucleic acids will then be isolated, hydrolyzed and examined for radioactivity. The ability of ascorbic acid to modify the excretion of the glucuronic acid conjugate of N-hydroxy-4-aminobiphenyl in dogs is being studied also.